Paper manufacture



Patented June 23, 1936 UNITED STATES of Massachusetts This inventionrelates to the production of sized paper filled with alkaline filler.

The principal object of this invention is to produce sized paper filledwith alkaline filler in which the sizing is applied to the paper web.

A further object is to avoid the necessity for the heating of the paperweb to a temperature sufficient to flux any thermoplastic materialemployed'as sizing agent.

A further object is the production ofv sized paper filled with alkalinefiller by the application of non-thermoplastic sizing agent to the paperweb.

A further object is the application of the sizing agent to the paper webin solution form, particularly in solution in an organic solvent.

Other objects and advantages of this invention will become apparentduring the course of the following description.

In my copending application, Serial No. 487,377, filed October 8, 1930,of which the present ap plication is a continuation in part, I havedescribed a method whereby paper filled with alkaline filler may besized by the application of thermoplastic material, such as paraflln, inliquid association to a paper web containing alkaline filler. By "liquidassociatio I mean that the thermoplastic material is present as sucheither in the form of an emulsion or solution. n the case of emulsions,or solutions in waterto the wet or to the already substantially driedeb; in the case of solutions made with solvents iscible with water,application is made only the already substantially dried web. After heevaporation of the liquid, a sized web reults. In order to secureuniformity of sizing, he web is raised to a temperature sufficiently ighto flux the thermoplastic material.

Further development of the above process has hown that sized paperfilled with alkaline filler n which the sizing'is substantially uniformmay e produced even when the paper web is not ubjected to a temperaturesufficiently high to ux the thermoplastic material. This has been oundto be particularly so in certain cases where .re employed. The necessityof subjecting the ab to such fiuxing temperature appears to dend amongother things somewhat upon the ature of the solvent employed butchiefly'upon he nature ofv the thermoplastic material used. ertainsolvents appear to have the property of fleeting more uniformdistribution of the ther- 1 oplastic material in the web, and likewisecer I iscible solvents, the application is made either olntions ofthermoplastic material in a solvent PATENT OFFICE PAPER MANUFACTUREHarold Robert Rafton, Ando ver, Mass, assignor to Raffold ProcessCorporation, a corporation No Drawing. Application May 5, 1932, SerialNo. 609,555

32 Claims. (Ci. 91-68) tain thermoplastic materials seem to distributethemselves more uniformly in the web than do others even whenthe samesolvent is employed.

Although I do not-wish to be limited by any,

generalization, I have, noted that apparently cer- 5 tain materials of awaxy nature seem to have their sizing distribution in the web improvedby fiuxing, whereas certain materials of a resinous nature seem todistribute themselves substantially uniformly in the web when insolution and do not appear to need fluxing.

The latter condition appears to be true where a resin such as'rosin isused in solution in ,a solvent, in which case only enough heat may besupplied to the web to evaporate the solvent without it being necessaryto actually raise the temperature of the web to the fluxing or socalledsintering temperature of the rosin. Of course if such temperature shouldbe reached, this is usually not objectionable; but as such temperatureis not ordinarily reached in the evaporation of low boiling pointorganic solvents such as may conveniently be used in the practice of myprocess, and particularly where the solvent is evaporated under reducedpressure, it is not necessary simultaneously or subsequently to supplythe necessary heat so thatthe web will reach such temperature. Any oneof a number of solvents may be used, among which the chlorinatedhydrocarbons such as carbon tetrachloride, ethylene dichloride, and thelike, may be recommended as being particularly satisfactory. Inthe-preferred practice of my invention a web containing alkaline filleris formed, for example by feeding to the web-forming device of a papermachine a fibrous mix in which alkaline filler is present. In this web'asolution of thermoplastic material in a solvent, for example rosin inethylene dichloride, is applied. The liquid content of the web is thenevaporated and a 40 sized paper web filled with alkaline filler results.The point of application, the method of application, the concentrationand amount of thermoplastic material to be applied, and other necessaryor optional details of my process, are similar in general to thoseemployed in my above referred to copending application, but for the sakeof completeness will be fully set forth immediately below together withcertain other features which I have found desirable.

The thermoplastic material may be applied in a solvent, which is usuallyorganic, as the thermoplastic materials I employ are normallysubstantially insoluble in water. If the material be applied in awater-miscible organic solvent, such for example as ethyl alcohol, itmay be applied at any convenient point on the paper machine either wherethe web is still in wet condition, for example at or just after thepress rolls, or at a point where water has been substantially removedfrom the web, for example preferably just after the' driers; or thesolution of the material may optionally be applied to the paper websubsequent to the paper machine by a separate process.

' In the case where a water-miscible solvent is employed and thesolution is applied to the wet web, the wet web may then be dried asusual, and in the interest of economy suitable means should be providedfor recovery of the solvent from the evaporated liquid. In the case ofapplication of a solution containing such solvent to a dried web,provision must be made for subsequent removel of the solvent from theweb, for example by passage of the web over driers or by festooning in ahot atmosphere, or the like. In any case, in the interest of economy,suitable solvent recovery means should be provided.

In the case of the use of a solution of thermoplastic material in asolvent substantially immiscible with water, and this is the type ofsolvent which I find it most convenient to employ, it is not suitable toapply such a solution to the wet web but it should be applied rather tothe web after the web has been substantially deprived of its water,preferably subsequent to the paper maclers, and then provision must bemade for removing the solvent such as by passage of the web over driersor through a hot atmosphere, with suitable provision for recovering thesolvent. However, in some cases the application of the solution of thethermoplastic material may take place as an independent processsubsequent to the paper machine operation, suitably by a coating orsaturating machine in which means is provided for subsequent removal andrecovery of the solvent.

The solution of the thermoplastic material may be applied to the web byany of the various methods for applying liquids to a paper web, such asby passing the web through a trough or vat containing the solution, orby applying the solution by a brush, .for example by a rotary brush, orby a contact roll or rolls, or by spraying or the like, or in the caseof water miscible solvents by a supply box' at one or more of the pressrolls. The method of application employed in any given instance is'thatwhich is best adapted for use at the particular point at which thesolution is applied and should be chosen with regard to the particularconditions to be met'in any given case, all of .which will be apparentto one skilled in the art. For example, I have found that theapplication by a trough followed by a pair of squeeze rolls is aconvenient method of application, especially for use with solutions inwater-immiscible solvents which are applied to the dry web.

The concentration of the solutions used depends to a certain extent uponthe method of employing them andthe point of application. Forapplication by a 'roll, the solutions may in general be moreconcentrated, but for immersion or spraying it is more suitable to havethem relatively dilute. An example of a. suitable solution concentrationto be applied by a contact roll is 10 per cent. of thermoplasticmaterial by weight, whereas for applying by a trough a 5 per cent.concentration by weight is suitable. I do not, however, limit myself tothese concentrations and they may be widely varied according tocircumstances as indicated above and still produce satisfactory results,

.uents, the percentage of filler, and the like, but

of thermoplastic material to be applied.

' able means such as a pump should be employed for supplying the agentto the applying device, and

The amount of thermoplastic material required for sizing varies somewhatas will be apparent, with the grade of paper made, its fibrous constit-As the solution of the thermoplastic material is 1 preferably appliedcontinuously to the web, suitthe amount of agent applied shouldpreferably vary regularly with the paper machine speed and 2 beadjustable to the various grades and weights of paper run. Other thingsbeing equal, after proper adjustments are made, the amount ofthermoplastic material applied may perhaps be most convenientlyregulated by regulating the concentra- 2 tion of the solution employed.

In the case of a solution of thermoplastic material in a water-misciblesolvent applied to a wet web, the evaporation of the solvent and theassociated water is suitably accomplished by the application to thepaper web of heat or reduced pressure or both such,'for example, as onthe ordinary paper machine drier or in a vacuum drier, in either casewith suitable means for the recovery 1 of the solvent. Where thesolution is applied to the already substantially dried web, such as maybe the case when a water-miscible solvent, and must be the case when awater-immiscible solvent, is employed, there is not present anysubstantial amount of moisture and thus the means for evaporation of thesolvent from the web as well as the recovery means are somewhatsimplified. Moreover, the amount of heat required for the evaporation ofthe solvent over that for the joint evaporation of solvent and water isconsiderably lessand thus smaller drying capacity is necessary. In thiscase, as in the case of the wet 'web application mentioned above, theevaporation of the solvent is suitably accomplished by the applicationto the paper web of heat or reduced pressure or both. An evacuatedchamber such as a vacuum drier or the like may be employed, operated aspart of the paper machine equipment or as a separate unit. Or my processmay be carried out with less capital expenditure by means ofsolvent/evaporating apparatus operated in an enclosure which ismaintained at substantially atmospheric pressure or just slightly below.A suitable apparatus for this purpose is described in my copendingapplication Serial No. 640,714, filed Nov. 1, 1932. Such apparatus maybe operated-as part of the paper machine equipment or as a separate stepafter the paper machine.

Whether atmospheric pressure or vacuum solvent evaporating apparatus beused suitable solvent recovery means should of course also be provided.

and is similar in appearance to and by ordinary observation cannot v bereadily distinguished from ordinary sized paper hitherto made by othermeans, for example, from clay filled paper sized by the ordinary method'of resin sizing in the definition thereof given above and is intendedto exclude paper which is saturated or substantially saturated with thesizing agent in question. And where in the claims I speak of applyingsizing agent in a solvent, as to a fibrous web, or distributing ittherein, I mean that the quantity of such sizing agent so applied ordistributed shall be insufficient to result in the production of papersaturated or substantially saturated with the sizing agent in question.It is to be understood that such sized paper as described herein isdistinct from the so-called surfacesized or coated paper which isproduced by applying animal or similar substantially water soluble sizeor a coating of similar nature to a paper web, either on the papermachine or subsequently by a separate process.

It is possible to employ my'sizing method for applying additional sizingto a web containing alkaline filler, which web is already partiallysized by other methods, and such use of my process falls withinthe scopeof by invention.

One advantage of my present improved process is that it simplifies myformer process, and requires less heat for carrying it out. Anotheradvantage is that it now opens up the possibility of using other sizingagents by this method which materials in themselves are notthermoplastic or, if thermoplastic do not flux readily at temperaturesordinarily employed in paper manufacture. Materials of the latter typeare for example cellulose compounds or derivatives, for example esterssuch as cellulose acetate, nitrate or the like, and these as well as thenon-thermoplastic materials may be dissolved in suitable solvents suchas organic solvents, applied to the 1 paper web, and the solventevaporated. Uniform sizing throughout the sheet is thus obtained despitethe fact that the material itself is substantially non-fluxible or notreadily fluxible at least at the temperature employed.

It is to be understood that I may if I desire actually apply heat to thesized substantially solvent-free web, providing that such heat is notsumcient substantially to flux the sizing agent employed.

In place of resins other thermoplastic mate- 7 rials may be used such asgums or the like, in-

eluding synthetic thermoplastics such as obtained for example bychemical condensation. In the case of non-thermoplastic sizing agents, Imay use any such, including synthetic nonthermoplastic materials, suchas for example as those obtained by chemical condensation.Nonthermoplastic materials are well known in the art, specific examplesbeing the product formed on standing from beta-elaeostearin, such asreferred to in Thorpe, Dictionary of Applied Chemistry, Vol. VII,Longmans,.Green 8: Co.,

New York,..192'7, page 227, last full sentence at bottom of secondcolumn; and infusible resins, such for example as the Baekelandinfusible resin, referred to in Ellis, Synthetic Resins and TheirPlastics", The Chemical Catalogue Co. 1110., N. Y., 1923, page 126, lastparagraph. Also I may employ mixtures of thermoplastic andnonthermoplastic material if desired; and in certain cases mixtures ofother material with either thermoplastic or non-thermoplastic material,said other material serving to modify the characteristics of saidthermoplastic or non-thermoplastic material in known manner, such as inrespect to plasticity, thermoplasticity, solubility, chemicalcomposition and the like. Whereas I may use either thermoplastic ornon-thermoplastic s izing agents substantially inert to alkali, this isnot necessary as the agents I use may be reactive with alkali. In theiatter case where such agents in the broke from my sized paper filledwith alkaline filler are reintroduced in the beater, they may tend toreact with the alkaline filler to cause foam, which however, can becontrolled by suitable means such, for example, as

by the addition of acidic material such as alum at the dilute stage ofthe papermaking process as has already been disclosed in one or more ofmy issued patents.

It is to be'understood, however, in respect to sizing agents which aresaponifiable, such for extended to be confined to that condition inwhich it is substantially unreacted uponby alkali.

Where I speak of synthetic thermoplastic material such as obtained bychemical condensation (an example of which is the condensation of analdehyde with a phenol), I mean to include material originally liquid orthermoplastic which may eventually become non-thermoplastic afterapplication to the web.

Where I speak of sizing agents herein, such as for example eitherthermoplastic or nonthermoplastic material, I mean to confine saidagents to material which is substantially insoluble in water. Inasmuchasv the sizing agents I employ are thus substantially water insoluble,naturally where I used the word solvent in connection with thesematerials, I mean to confine myself to solvents other than water whichat temperatures sufliciently high to substantially injure the web, theresulting process would not be operative for the intended purpose.Therefore, I disclaim the use of solvents except those havingsufficiently high vapor pressure, that is to say sufficiently lowboiling point, that they may be substantially removed from the Web forexample by at least one of the herein described procedures at atemperature which will not be sufliciently high to substantially injurethe web.

By the term alkaline filler" I mean substantially water insoluble fillerwhich when agitated in contact with freshly boiled distilled water, sayfor an hour, will impart a pH value to such water greater than 7.0, thatis, which will be on the alkaline side of the neutral point. 'Amongfillers in this group may be mentioned calcium carbonate, of which limemud from the causticizing process is one form; calcium carbonatemagnesium basic carbonate employed in the paper disclosed in my UnitedStates Patent No. 1,595,416,

issued August 10, 1926; calcium carbonate magnesium hydroxide disclosedin my United States Patent No. 1,415,391, issued May 9, 1922; and othersubstantially water insoluble normal or basic carbonates of alkalineearth metals, (which expression is herein intended to include magnesium)or compounds, double salts, or other physically associated mixtures ofthese with one or more other acid soluble materials of a substantiallywater insoluble nature. By the term alkaline filler I also intend toinclude fibrous material and/or other material such as paper coatingconstituents or the like containing one or more compounds of thecharacter referred to, such as old papers or similar papers, broke", orthe like.

When I use the word paper herein, I use it in the broad sense to includeproducts of manufacture of all types and of all weights and thicknesses,which contain as an essential constituent a considerable amount ofprepared fibre and which are capable of being produced on a Fourdrinier,cylinder, or other forming, felting, shaping or molding machine. 7

While I have described in detail the preferred embodiment of myinvention, it is to be under-; stood that the details of procedure, theproportions of ingredients, and the arrangement of steps may be. widelyvaried without departing from the spirit of the invention or the scopeof the subjoined claims.

I claim:

1. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent dissolved in asolvent therefor, said sizing agent in such solution being characterizedby beingcapable of distributing itself in said web to impart asubstantially uniform sizing effect thereto at a temperature at which nosubstantial fluxing of said sizing agent occurs, said sizing agent insuch solution being further characterized by being substantiallyunreacted upon by alkali, and evaporating substantially completely theliquid content of said web, but without bringing about any.substantialfluxing of said sizing agent in said web, said sizing agent applied tosaid web being sufficient in amount to impart sizing effect to saidpaper.

2. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent dissolved in asolvent therefor, said sizing agent in such solution being characterizedby being capable of distributing itself in said web to impart asubstantially uniform sizing effect thereto at a. temperature at whichno substantial fluxing of said sizing agent occurs, said sizing agent insuch solution being further characterized by being substantiallyunreacted upon by alkali, and evaporating substantially completely theliquid content of said web by means of reduced pressure and heat, saidheat being insufficient to bring about any substantial fluxing of saidsizing agent in said web, said sizing agent applied to said web beingsufficient in amount to impart sizing effect to said paper.

3. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent dissolved in a solventtherefor, said sizing agent in such solution being characterized bybeing capable of distributing itself in saidweb to impart asubstantially uniform sizing effect thereto at a temperature at which nosubstantial fiuxing of said sizing agent occurs, said sizing agent insuch solution being further characterized by being substantiallyunreacted upon by alkali, and evaporating substantially completely saidsolvent content of said web, but without bringing about any substantialfluxing of said sizing agent in said web, said sizing agent applied tosaid web being sufficient in amount to impart sizing effect to saidpaper.

4. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent in such solution beingcharacterized by being capable of distributing itself in said web toimpart a substantially uniform sizing effect thereto at a temperature atwhich no substantial fiuxing of said sizing agent occurs, said sizingagent in such solution being further characterized by beingsubstantially unreacted upon by alkali, and evaporating substantiallycompletely said solvent content of said web by means of reduced pressureand heat, said heat being. insufficient to bring about any substantialfluxing of said sizing agent in said web, said sizing agent applied tosaid web being suificient in amount to impart sizing effect to saidpaper.

5. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent dissolved in organic solvent,said sizing agent in such solution being characterized by being capableof distributing itself in said web to impart a substantially uniformsizing effect thereto at a temperature at which no substantial fiuxingof said sizing agent occurs, said sizing agent in such solution beingfurther characterized by being substantially unreacted upon by alkali,and evaporating substantially completely said organic solventcontent ofsaid web by means of heat, said heat being insuflicient to bring aboutany substantial fiuxing of said sizing agent in said web, said sizingagent applied to said web being sufllcient in amount to impart sizingeffect to said paper.

6. The steps in a method of manufacturing sized paper filled withalkaline filler comprising distributing substantially water insolublesizing agent in a fibrous web containing alkaline filler by means of avehicle comprising organic solvent in which said sizing agent issoluble,,said sizing agent being characterized by being capable ofdistributing itself by 'means of said vehicle in said web to impart asubstantially uniform sizing effect thereto at a temperature at which nosubstantial fluxing of said sizing agent occurs, said sizing agent beingfurther characterized by being in a condition in which it issubstantially unreacted upon by alkali, and evaporating substantiallycompletely said organic solvent content of said web, but withoutbringing about any substantial fluxing of said sizing agent in said web,said sizing agent distributed in said web being sufficient in amount toimpart sizing effect to said paper.

'I. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said websubstantially water insoluble sizing agent comprisingthermoplastic material dissolved in a solvent therefor, said sizingagent in such solution being characterized by being capable ofdistributing itself in said web to impart a substantially uniform sizingeffect thereto at a temperature at which no substantial fluxin'g of saidsizing agent occurs, and evaporating substantially completely the liquidcontent of said web, but without bringing about any substantial fluxingof said thermoplastic material in said web, said sizing agent applied tosaid web being sufficient in amount to impart sizing effect to saidpaper.

8. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent comprisingthermoplastic material dissolved in a solvent therefor, said sizingagent in such solufilled with alkaline filler comprising preparing a'flbrous web containing alkaline filler, substantial- 1y drying saidweb, applying to said substantially dry web substantially waterinsoluble sizing agent comprising thermoplastic material dissolved in asolvent therefor, said sizing agent in such solution being characterizedby being capable of distributing itself in said web to impart'asubstantially uniform sizing effect thereto at a temperature at which nosubstantial fiuxingof said sizing agent occurs, and evaporatingsubstantially completely said solvent content of said web, but withoutbringing about any substantial fiuxing of said thermoplastic material insaid web, said sizing agent applied to said web being sufficient inamount to impart sizing 'eifect to said paper.

10. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web,'applying to said substantially dry websubstantially water insoluble sizing agent comprising thermoplasticmaterial dissolved in a solvent therefor, said sizing agent in suchsolution being characterized by being capable of distributing itself insaid web to impart a substantially uniform sizing effect thereto at atemperature at which no substantial fluxing of said sizing agent occurs,and evaporating substantially completely said solvent content of saidweb by means of reduced pressure and heat, said heat being insuflicientto bring about any substantial fluxing of a fibrous web containingalkaline filler, substansaid thermoplastic material in said web, saidsizing agent applied to said web being sufllcient in amount to impartsizing eifect to said paper.

11. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising thermoplasticmaterial dissolved in organic solvent, said sizing agent in suchsolution being characterized by being capable of distributing itself insaid web to impart a substantially uniform sizing eifect thereto at atemperature at which no substantial fluxing of said sizing agent.occurs, and evaporating substantially completely said organic solventcontent of said web by means of heat, said heat being insuflieient tobring about any substantial fiuxing of said thermoplastic material insaid web, said sizing agent applied to said web being sufficient inamount to impart sizing eifect to said paper.

12. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially ing itselfin said web to impart a substantially uniform sizing effect thereto at atemperature at which no substantial fluxing of said sizing agent occurs,and evaporating substantially completely said organic solvent content ofsaid web by means of reduced pressure and heat, said heat beinginsufficient to bring about any substantial fluxing of saidthermoplastic material in said web, said sizing agent applied to saidweb being sumcient in amount to impart sizing eifect to said paper.

13. The method of'manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent comprising rosindissolved in a solventtherefor, and evaporating substantially completelythe liquid content of said web, 'but without bringing about anysubstantial fiuxing of said rosin in said web, said sizing agent appliedto said web being sufiicient in amount to impart sizing eifect to saidpaper. 14. The method of manufacturing sized paper filled with alkalinefiller comprising preparing a fibrous web containing alkaline filler,apply ng to said web substantially water insoluble sizing agentcomprising rosin dissolved in a solvent therefor, and evaporatingsubstantially completely the liquid content of said web by means ofreduced pressure and heat, said heat being insuflicient to bring aboutany substantial fluxing of said rosin in said web, said sizing agentapplied to said web being sufficient in amount to impart sizing effectto said paper.

15. The method of manufacturing sized paper filled with alkaline fillercomprising preparing tially drying said web, applying to saidsubstantially dry'web substantially water insoluble sizing agentcomprising rosin dissolved in a solvent therefor, and evaporatingsubstantially completely said solvent content of said web, but withoutbringing about any substantial fluxing of said rosin in said web, saidsizing agent applied to said web being suiiicient in amount to impartsizing I effect to said paper.

16. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising rosin dissolved ina solvent therefor, and evaporating substantially completely saidsolvent content of said web by means of reduced pressure and heat, saidheat being insufficient to bring about any substantial fiuxing of saidrosin in said web, said sizing agent applied to said web beingsufiicient in amount to impart sizing effect to said paper.

17. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising rosin dissolved inorganic solvent, and evaporating substantially completely said organicsolvent content of said web by means of heat, said heat beinginsuflicient to bring about any substantial fiuxing of said rosin insaid web, said sizing agent applied to said web being suflicient inamount to impart sizing effect to said paper.

18. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising rosin dissolved inorganic solvent, and evaporating substantially completely said organicsolvent content of said web by meansoi reduced pressure and heat, saidheat being insufficient to bring about any substantial fiuxing of saidrosin in said web, said sizing agent applied to said web beingsufficient in amount to impart sizing effect to said paper.

19. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent comprisingnon-thermoplastic material dissolved in a solvent therefor, said sizingagent in such solution being characterized by being substantiallyunreacted upon by alkali, and evaporating substantially completely theliquid c'on-,

tent of said web, said sizing agent applied, to said web being sumcientin amount to impart sizing effect to said paper. v

20. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a. fibrous web containing alkaline filler,applyingto said web substantially water insoluble sizing agentcomprising non-thermoplastic material dissolved in'a solvent therefor,said sizing agent in such solution being characterized by beingsubstantially unreacted upon by alkali, and evaporating substantiallycompletely the liquid content of said web by means of reduced pressureand heat, said sizing agent applied to said web being sufiicient inamount to impart sizing effect to said paper.

21. The method of manufacturing sized paper filled with alkaline fillercomprising-preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising non-thermoplasticmaterial dissolved in a solvent therefor, said sizing agent in, suchvsolution being characterized by being-substantially unreacted upon byalkali, and evaporating substantially completely said solvent content ofsaid web by means of heat, said sizing cient in agent applied to saidweb being sufficient in amount to impart sizingeflfect to said paper.

22. The method of manufacturing sized paper filled with alkaline filler,comprising preparing a fibrous web containing alkaline filler,substantially drying said web, applying to said substantially dry websubstantially water insoluble sizing agent comprising non-thermoplasticmaterial dissolved in a solvent therefor, said sizing agent in suchsolution being characterized by being substantially unreacted upon byalkali, and evaporating substantially completely said solvent content ofsaid web by means of reduced pressure and heat, said sizing agentapplied to said web being sufficient in amount to impart sizing effectto said paper.

23. The method of manufacturing sized paper filled with alkaline fillercomprising preparing a. fibrous web containing alkaline filler,substantially drying said web, applying to said substantially 20 dry websubstantially water insoluble sizing agent comprising non-thermoplasticmaterial dissolved in organic solvent, said sizing agent in suchsolution being characterized by being substantially unreacted upon byalkali, and evaporating sub- 25 stantially completely said organicsolvent content of said web by means of heat, said sizing agent appliedto said web being sumcient in amount to impart sizing efifect to saidpaper.

24. The steps in a method of manufacturing 30 sized paper filled withalkaline filler comprising distributing substantially water insolublesizing agent comprising non-thermoplastic material in a fibrous webcontaining alkaline filler by means of a vehicle comprising organicsolvent in which 35 said sizing agent is soluble, said sizing agentbeing characterized by being in a condition in which it is substantiallyunreacted upon by alkali, and evaporating substantially completely saidorganic solvent content of said web, said sizing agent distributed insaid web being sufiicient in amount to impart sizing effect to saidpaper.

25. Sized filled paper comprising fibrous material, alkaline filler, andsizing comprising substantially water insoluble cellulose derivativedeposited out of a solution thereof in a solvent.

26. Sized filled paper comprising fibrous material, alkaline filler, andcellulose ester deposited out of a solution thereof in a solvent.

27. Sized filled paper comprising fibrous material, alkaline filler, andsizing comprising substantially water insoluble non-thermoplastic ma.-terial substantially unreactive with alkali.

28. Sized filled paper comprising fibrous material, alkaline filler, andsizing comprising synthetic substantially water insolublenon-thermoplastic material -substantially unreactive with alkali.

' 29. Sized filled paper resulting from applying to a fibrous webcontaining alkaline filler substantially water insoluble sizing agentdissolved in a solvent therefor, said sizing agent in such solutionbeing characterized by being capable of distributing itself in said webto impart a substantially uniform sizing eflect thereto at atemperature'at which no substantial fiuxing of said sizing agent occurs,said sizing agent in such solution being further characterized by beingsubstantially unreacted upon by alkali, and subsequently substantiallyremoving said solvent from 70 said web, but without bringing about anysubstantial fiuxing of said sizing agent in said web, said sizing agentapplied to saidweb being su flamount to impart sizing effect to saidpaper. 76

30. Sized filled paper resulting from distributing substantially waterinsoluble sizing agent which comprises non-thermoplastic material in acondition in which it is substantially unreacted upon by alkali in afibrous web containing alkaline filler by means of a vehicle comprisinga solvent in which said sizing agent is soluble, and subsequentlysubstantially removing said solvent from said web, said sizing agentdistributed in said web being suflicient in amount to impart sizingeffect to said paper.

31. Paper filled with alkaline filler comprising fibrous material,alkaline filler, and substantially water insoluble sizing agent, saidsizing agent having been provided by deposition out of solution thereofin an organic solvent by substantially completely removing said solventby evaporation,

' said sizing agent in such solution being char,-

acterized by being substantially unreacted upon by alkali, said sizingagent being further characterized by being capable of imparting asubstantially uniform sizing effect at a temperature at which nosubstantial fiuxing of said sizing agent occurs.

32. Paper filled with alkaline filler comprising fibrous material,alkaline flller sizing, and, additionally, substantially water insolublesizing agent, said sizing agent having been provided by deposition outof solution thereof in an organic solvent by substantially completelyremoving said solvent by evaporation, said sizing agent in such solutionbeing characterized by being substantially unreacted upon by alkali,said sizing agent being further characterized by being capable ofimparting a substantially uniform sizing effect at a temperature atwhich no substantial fluxing of said sizing agent occurs.

HAROLD ROBERT RAFI'ON.

